MLX75031 Datasheet, PDF (24/67 Pages) Melexis Microelectronic Systems – Optical Gesture & Proximity Sensing IC

MLX75031
Optical Gesture & Proximity Sensing IC
with Integrated LED Drivers
Datasheet
The overall transfer function for the LED temperature sensing is defined by following formula:
V_LED
=
(ADC _ LEDTEMP − 32768)× 6.64
65535× G _ ADJ _ LED
+
2 × OS
_
ADJ
_
LED
• V_LED : the voltage between pin Drive_LEDA/B and pin ShuntR (in V)
• ADC_LEDTEMP : the decimal value of the LED temperature measurement (see Output Data Frame
of read-out)
• G_ADJ_LED: the gain value selected by the SetPLS register
• OS_ADJ_LED: the offset value selected by the SetPLS register (in V)
Due to different LED types and LED connections, the gain G_ADJ_LED and OS_ADJ_LED shall be set such that
the measurement range fits the application the best way.
Minimum V_LED measurement resolution is typical 0.5mV.
8.5.4. Battery Supply Voltage Measurement & Monitoring
The voltage on the VSUP pin is continuously monitored. In case the voltage on the pin goes above 20V
typical, the error flag Err_VsupH will be set and the LED driver will be shut off. Active Light measurements
can still be executed but the LED driver will be disabled as long as VSUP > 20V typical, protecting the LED's
from being damaged.
The error flag Err_VsupL will be set when the voltage on VSUP goes below the threshold defined by the two
bits VSUPLOW<1:0>. The LED driver will remain active. Active Light measurements are still possible.
In Figure 6 the definition of the thresholds is shown. It is indicated when the certain error conditions are
present and when the error flags are set.
VSUP voltage
Error condition on high threshold
Error condition on low threshold
LED driver is disabled
in this time
Err_VsupH is set
Err_VsupL is set
VTSUPH=20V
VTSUPH-VTSUPH_hys=18.5V
VTSUPL+VTSUPL_hys=6.75V
VTSUPL=6V
Time
Figure 6 : Threshold definitions of VSUP monitoring block
REVISION 001 – JANUARY, 2013
39010xxxxx
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